Yeah like paige said you will get in when its time but usually around level 28 or so all the nautical battles are level 26-28 or so. make sure your nautical level is at least 24 to be competitive. If not youll need help with nautical battles.
It isn't so much your level as it is finishing the main questline quest that sends you there. Often a promotion or other "special" quest will refer you to a region you cannot access yet because you are not far enough along in the main quest line.
I have a quest in Port Regal. I cant get in. Do i need to be a certain level? I am level 22 now
After the first part of Cool Ranch you'll be able to come there. I was about a level 25 when I first was able to go to Port Regal (I did the main quests only, heh) but I've seen others go there at around a level 30. There will be a very exciting adventure waiting there for you